The aims of this proposal are twofold: 1) To characterize in terms of function and cellular phenotype the cells which infiltrate rejecting sponge matrix allografts, 2) To determine these influences acting on the infiltrating cells which induce them to leave the lymphoid tissue, migrate to, and enter the graft. The model utilizes a sponge coated with allogenic cells of defined antigenic type which is implanted subcutaneously into recipient mice. The matrices of the sponge allograft provide a harbor for the infiltrating cells so that the grafts can be excised and the infiltrating cells removed without mechanical or chemical changes. The capacity of these cells: a) To kill targets, b) proliferate in response to antigens, c) suppress prolifieration, d) migrate in a chemotactic gradient in vitro and e) migrate to sponge grafts in vivo after characterization in vitro can be assessed. The influences of time after grafting, genetic barrier, and host cell-graft interactions can be determine. Of particular interest are the genetic determinants of lymphocyte migration to a graft in vivo; the functional and phenotypic characteristics of rapidly migrating lymphocytes in vitro; and the nature of the chemotactic factors which influence the movement of specifically sensitized lymphocytes.